Osteosarcomas are highly aggressive and heterogeneous bone malignancies with limited treatment options. Current therapies primarily rely on cisplatin and doxorubicin, which frequently lead to drugresistant phenotypes and metastasis, reducing treatment effectiveness and patient survival [1,2]. To explore drug resistance mechanisms, cisplatin resistance was induced in osteosarcoma cell lines (five established and eight patient-derived xenografts, PDXCL) through continuous exposure to gradually increasing drug concentrations. Cell viability and resistance index (RI) were assessed after 72 hours. Cisplatin uptake was analyzed via single-cell ICP-MS, while proteomics (LC-Q-TOF) identified protein changes linked to Pt uptake, potentially serving as predictive biomarkers for treatment response. 

Our data showed that after 1-8 months of cisplatin exposure, ~54% of the cell lines (5/5 established and 2/8 PDXCL) developed stable drug resistance, with similar RI values for cisplatin (3.67±1.22) and up to 131 RI for doxorubicin treatment [3]. Differential cisplatin uptake patterns were observed for all the cell pairs (sensitive/resistant), with variations ranging from a 10-fold increase to a 7-fold decrease in resistant vs sensitive models. Intercellular variations were consistently lower in resistant models compared to sensitive ones. Complementarily, the proteomic analysis identified 8,033 common proteins for sensitive and resistant lines and a 192-protein response signature. Proteins linked to cisplatin uptake and efflux were associated with lower Pt levels, while detoxification mechanisms (e.g. sequestration) correlated with higher Pt content. High heterogeneity in protein expression was observed in resistant models, with PDXCL lines showing greater sensitivity to treatments [1,2].

In conclusion, our research provided new insights into drug resistance and offered a potential pathway for improving osteosarcoma treatment through personalized medicine approaches. Further preliminary experiments were conducted to address the penetration capabilities of cisplatin in osteosarcoma 3D spheroids aiming to better mimic tumoral structures.

References

[1] A. Abarrategi, J. Tornín, L. Martinez-Cruzado, et al. Stem Cells Int. 2016 (2016), 3631764.

[2] C. López-Portugués, P. Díez, M. Montes-Bayón, Proteomes, 2024, 12(1), 8.

[3] B. Gallego, D. Murillo, V. Rey, et al. Int J Mol Sci, 23 (2022), 6425.